The Obama administration secretly won permission from a surveillance court in 2011 to reverse restrictions on the National Security Agency’s use of intercepted phone calls and e-mails, permitting the agency to search deliberately for Americans’ communications in its massive databases, according to interviews with government officials and recently declassified material.

In addition, the court extended the length of time that the NSA is allowed to retain intercepted U.S. communications from five years to six years — and more under special circumstances, according to the documents, which include a recently released 2011 opinion by U.S. District Judge John D. Bates, then chief judge of the Foreign Intelligence Surveillance Court.

What had not been previously acknowledged is that the court in 2008 imposed an explicit ban — at the government’s request — on those kinds of searches, that officials in 2011 got the court to lift the bar and that the search authority has been used.

Together the permission to search and to keep data longer expanded the NSA’s authority in significant ways without public debate or any specific authority from Congress. The administration’s assurances rely on legalistic definitions of the term “target” that can be at odds with ordinary English usage. The enlarged authority is part of a fundamental shift in the government’s approach to surveillance: collecting first, and protecting Americans’ privacy later.

“The government says, ‘We’re not targeting U.S. persons,’ ” said Gregory T. Nojeim, senior counsel at the Center for Democracy and Technology. “But then they never say, ‘We turn around and deliberately search for Americans’ records in what we took from the wire.’ That, to me, is not so different from targeting Americans at the outset.”

Opinion struck down an NSA program that unlawfully gathered thousands of electronic communications between Americans.

The court decision allowed the NSA “to query the vast majority” of its e-mail and phone call databases using the e-mail addresses and phone numbers of Americans and legal residents without a warrant, according to Bates’s opinion.

The queries must be “reasonably likely to yield foreign intelligence information.” And the results are subject to the NSA’s privacy rules.

The court in 2008 imposed a wholesale ban on such searches at the government’s request, said Alex Joel, civil liberties protection officer at the Office of the Director of National Intelligence (ODNI). The government included this restriction “to remain consistent with NSA policies and procedures that NSA applied to other authorized collection activities,” he said.

But in 2011, to more rapidly and effectively identify relevant foreign intelligence communications, “we did ask the court” to lift the ban, ODNI general counsel Robert S. Litt said in an interview. “We wanted to be able to do it,” he said, referring to the searching of Americans’ communications without a warrant.

Joel gave hypothetical examples of why the authority was needed, such as when the NSA learns of a rapidly developing terrorist plot and suspects that a U.S. person may be a conspirator. Searching for communications to, from or about that person can help assess that person’s involvement and whether he is in touch with terrorists who are surveillance targets, he said. Officials would not say how many searches have been conducted.

The court’s expansion of authority went largely unnoticed when the opinion was released, but it formed the basis for cryptic warnings last year by a pair of Democratic senators, Ron Wyden (Ore.) and Mark Udall (Colo.), that the administration had a “back-door search loophole” that enabled the NSA to scour intercepted communications for those of Americans. They introduced legislation to require a warrant, but they were barred by classification rules from disclosing the court’s authorization or whether the NSA was already conducting such searches.

“The [surveillance] Court documents declassified recently show that in late 2011 the court authorized the NSA to conduct warrantless searches of individual Americans’ communications using an authority intended to target only foreigners,” Wyden said in a statement to The Washington Post. “Our intelligence agencies need the authority to target the communications of foreigners, but for government agencies to deliberately read the e-mails or listen to the phone calls of individual Americans, the Constitution requires a warrant.”

Senior administration officials disagree. “If we’re validly targeting foreigners and we happen to collect communications of Americans, we don’t have to close our eyes to that,” Litt said. “I’m not aware of other situations where once we have lawfully collected information, we have to go back and get a warrant to look at the information we’ve already collected.”

The searches take place under a surveillance program Congress authorized in 2008 under Section 702 of the Foreign Intelligence Surveillance Act. Under that law, the target must be a foreigner “reasonably believed” to be outside the United States, and the court must approve the targeting procedures in an order good for one year.

But — and this was the nub of the criticism — a warrant for each target would no longer be required. That means that communications with Americans could be picked up without a court first determining that there is probable cause that the people they were talking to were terrorists, spies or “foreign powers.”

That is why it is important to require a warrant before searching for Americans’ data, Udall said. “Our founders laid out a roadmap where Americans’ privacy rights are protected before their communications are seized or searched — not after the fact,” he said in a statement to The Post.

Another change approved by Bates allows the agency to keep the e-mails of or concerning Americans for up to six years, with an extension possible for foreign intelligence or counterintelligence purposes. Because the retention period begins “from the expiration date” of the one-year surveillance period, the court effectively added up to one year of shelf life for the e-mails collected at the beginning of the period.

Joel said that the change was intended to standardize retention periods across the agencies and that the more generous standard was “already in use” by another agency.

The NSA intercepts more than 250 million Internet communications each year under Section 702. Ninety-one percent are from U.S. Internet companies such as Google and Yahoo. The rest come from “upstream” companies that route Internet traffic to, from and within the United States. The expanded search authority applies only to the downstream collection.

Barton Gellman contributed to this report.

Ellen Nakashima is a national security reporter for The Washington Post. She focuses on issues relating to intelligence, technology and civil liberties.

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